Cell and gene therapy products must be tested for sterility, stability, purity and potency. In addition, it is important to test clinical cell therapy products for identity, consistency and comparability. Testing cellular and gene therapies is challenging. These therapies are generally collected from a single person so the quantity of material available to test is limited. They are typically transfused immediately or shortly after they are produced so there is a very limited amount of time to complete the assays. Many of these therapies are complex cells that have multiple functions. The cell functions that are critical to the clinical effectiveness of these therapies are often not known. Traditionally, analytic assays such as flow cytometry, ELISA, ELISPOT and cell culture have been used to analyze cellular and gene therapies. While these assays have proven to be very useful, the number and types of factors that can be analyzed with these assays is limited. We have been investigating the use of gene and micro RNA expression assays for the analysis of cellular therapies. These assays can require the use of only small quantities of cells and can be used to assess the expression of the entire transcriptome. We have been testing the ability of global gene and micro RNA expression profiling to determine the utility of these assays for assessing the stability, purity and potency of cellular therapies. We have shown that gene expression profiling can detect changes in stored cells and detect differences between peripheral blood leukocytes (T cells, B cells and monocytes) and hematopoietic stem cells. Gene expression profiling has also been able to detect differences between immature and mature dendritic cells (DCs) and has been useful for comparing mature DCs produced using different combinations of maturation agents. Chimeric Antigen Receptor (CAR) T cells are being used to treat a number of hematologic malignancies, however, clinical outcomes have varied among recipients of these therapies and some of this variability is likely due to variability, and hence, differences in potency among CAR T cell products. We are using gene expression analysis, mRNA analysis, single cell analysis, next generation sequencing and metabolomics to identify factors associated with the clinical potency of these cells. We have also developed an assay that measures the number of copies of the CAR vector that have integrated into the genome of each T cell. We are investigating methods to assess the sites of vector integration.